Implementation of the Salsa20 stream cipher

modified:   setup.py
modified:   lib/Crypto/SelfTest/Cipher/__init__.py
new file:   lib/Crypto/Cipher/Salsa20.py
new file:   lib/Crypto/SelfTest/Cipher/test_Salsa20.py
new file:   src/Salsa20.c
new file:   src/salsa20/ecrypt-config.h
new file:   src/salsa20/ecrypt-machine.h
new file:   src/salsa20/ecrypt-portable.h
new file:   src/salsa20/ecrypt-sync.h
new file:   src/streamIV_template.c